1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * srm_env.c - Access to SRM environment
4 * variables through linux' procfs
5 *
6 * (C) 2001,2002,2006 by Jan-Benedict Glaw <jbglaw@lug-owl.de>
7 *
8 * This driver is a modified version of Erik Mouw's example proc
9 * interface, so: thank you, Erik! He can be reached via email at
10 * <J.A.K.Mouw@its.tudelft.nl>. It is based on an idea
11 * provided by DEC^WCompaq^WIntel's "Jumpstart" CD. They
12 * included a patch like this as well. Thanks for idea!
13 */
14
15#include <linux/kernel.h>
16#include <linux/gfp.h>
17#include <linux/module.h>
18#include <linux/init.h>
19#include <linux/proc_fs.h>
20#include <linux/seq_file.h>
21#include <asm/console.h>
22#include <linux/uaccess.h>
23#include <asm/machvec.h>
24
25#define BASE_DIR "srm_environment" /* Subdir in /proc/ */
26#define NAMED_DIR "named_variables" /* Subdir for known variables */
27#define NUMBERED_DIR "numbered_variables" /* Subdir for all variables */
28#define VERSION "0.0.6" /* Module version */
29#define NAME "srm_env" /* Module name */
30
31MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
32MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
33MODULE_LICENSE("GPL");
34
35typedef struct _srm_env {
36 char *name;
37 unsigned long id;
38} srm_env_t;
39
40static struct proc_dir_entry *base_dir;
41static struct proc_dir_entry *named_dir;
42static struct proc_dir_entry *numbered_dir;
43
44static srm_env_t srm_named_entries[] = {
45 { "auto_action", ENV_AUTO_ACTION },
46 { "boot_dev", ENV_BOOT_DEV },
47 { "bootdef_dev", ENV_BOOTDEF_DEV },
48 { "booted_dev", ENV_BOOTED_DEV },
49 { "boot_file", ENV_BOOT_FILE },
50 { "booted_file", ENV_BOOTED_FILE },
51 { "boot_osflags", ENV_BOOT_OSFLAGS },
52 { "booted_osflags", ENV_BOOTED_OSFLAGS },
53 { "boot_reset", ENV_BOOT_RESET },
54 { "dump_dev", ENV_DUMP_DEV },
55 { "enable_audit", ENV_ENABLE_AUDIT },
56 { "license", ENV_LICENSE },
57 { "char_set", ENV_CHAR_SET },
58 { "language", ENV_LANGUAGE },
59 { "tty_dev", ENV_TTY_DEV },
60 { NULL, 0 },
61};
62
63static int srm_env_proc_show(struct seq_file *m, void *v)
64{
65 unsigned long ret;
66 unsigned long id = (unsigned long)m->private;
67 char *page;
68
69 page = (char *)__get_free_page(GFP_USER);
70 if (!page)
71 return -ENOMEM;
72
73 ret = callback_getenv(id, page, PAGE_SIZE);
74
75 if ((ret >> 61) == 0) {
76 seq_write(seq: m, data: page, len: ret);
77 ret = 0;
78 } else
79 ret = -EFAULT;
80 free_page((unsigned long)page);
81 return ret;
82}
83
84static int srm_env_proc_open(struct inode *inode, struct file *file)
85{
86 return single_open(file, srm_env_proc_show, pde_data(inode));
87}
88
89static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
90 size_t count, loff_t *pos)
91{
92 int res;
93 unsigned long id = (unsigned long)pde_data(inode: file_inode(f: file));
94 char *buf = (char *) __get_free_page(GFP_USER);
95 unsigned long ret1, ret2;
96
97 if (!buf)
98 return -ENOMEM;
99
100 res = -EINVAL;
101 if (count >= PAGE_SIZE)
102 goto out;
103
104 res = -EFAULT;
105 if (copy_from_user(to: buf, from: buffer, n: count))
106 goto out;
107 buf[count] = '\0';
108
109 ret1 = callback_setenv(id, buf, count);
110 if ((ret1 >> 61) == 0) {
111 do
112 ret2 = callback_save_env();
113 while((ret2 >> 61) == 1);
114 res = (int) ret1;
115 }
116
117 out:
118 free_page((unsigned long)buf);
119 return res;
120}
121
122static const struct proc_ops srm_env_proc_ops = {
123 .proc_open = srm_env_proc_open,
124 .proc_read = seq_read,
125 .proc_lseek = seq_lseek,
126 .proc_release = single_release,
127 .proc_write = srm_env_proc_write,
128};
129
130static int __init
131srm_env_init(void)
132{
133 srm_env_t *entry;
134 unsigned long var_num;
135
136 /*
137 * Check system
138 */
139 if (!alpha_using_srm) {
140 printk(KERN_INFO "%s: This Alpha system doesn't "
141 "know about SRM (or you've booted "
142 "SRM->MILO->Linux, which gets "
143 "misdetected)...\n", __func__);
144 return -ENODEV;
145 }
146
147 /*
148 * Create base directory
149 */
150 base_dir = proc_mkdir(BASE_DIR, NULL);
151 if (!base_dir) {
152 printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
153 BASE_DIR);
154 return -ENOMEM;
155 }
156
157 /*
158 * Create per-name subdirectory
159 */
160 named_dir = proc_mkdir(NAMED_DIR, base_dir);
161 if (!named_dir) {
162 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
163 BASE_DIR, NAMED_DIR);
164 goto cleanup;
165 }
166
167 /*
168 * Create per-number subdirectory
169 */
170 numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
171 if (!numbered_dir) {
172 printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
173 BASE_DIR, NUMBERED_DIR);
174 goto cleanup;
175
176 }
177
178 /*
179 * Create all named nodes
180 */
181 entry = srm_named_entries;
182 while (entry->name && entry->id) {
183 if (!proc_create_data(entry->name, 0644, named_dir,
184 &srm_env_proc_ops, (void *)entry->id))
185 goto cleanup;
186 entry++;
187 }
188
189 /*
190 * Create all numbered nodes
191 */
192 for (var_num = 0; var_num <= 255; var_num++) {
193 char name[4];
194 sprintf(buf: name, fmt: "%ld", var_num);
195 if (!proc_create_data(name, 0644, numbered_dir,
196 &srm_env_proc_ops, (void *)var_num))
197 goto cleanup;
198 }
199
200 printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
201 VERSION);
202
203 return 0;
204
205cleanup:
206 remove_proc_subtree(BASE_DIR, NULL);
207 return -ENOMEM;
208}
209
210static void __exit
211srm_env_exit(void)
212{
213 remove_proc_subtree(BASE_DIR, NULL);
214 printk(KERN_INFO "%s: unloaded successfully\n", NAME);
215}
216
217module_init(srm_env_init);
218module_exit(srm_env_exit);
219

source code of linux/arch/alpha/kernel/srm_env.c